Known diffuser attachments for hair dryers, for spreading and reducing the speed of air flow from the dryer nozzle, trap hot air and the dryer cuts off due to overheating.
Forsberg, U.S. Pat. No. 4,230,279, is directed to a diffuser attachment having a plurality of apertures on a face portion and a filter behind the face plate to provide resistance to the flow of air. The problem of overheating is not solved since there is no apparent way for cool air to enter or hot air to exit when the dryer is turned off. Barns et al., U.S. Pat. No. 4,602,146, describes a hand-held hair dryer having a nozzle portion enclosing diffuser vanes pivotally mounted within the nozzle.
The hair dryer of Hlavac, U.S. Pat. No. 3,943,329, has a diffuser section having a plurality of apertures on its face. Should the air exit on the face of the diffuser become partially or completely blocked, air flow exits through an annular space between a guard member and the nozzle. Laing, U.S. Pat. No. 3,284,611, describes a removable air deflector for a hair dryer attached by end members so that deflector members are spaced from the hair dryer casing allowing cool air to enter the deflector and mix with air leaving the dryer nozzle.
The patent to Gilbertson, U.S. Pat. No. 4,634,839, shows a handheld air dryer for use in drying small areas such as teeth, gums and mouth. The dryer has a plurality of opening exhaust vents for directing air away from the nozzle. In use, air is directed in a concentrated stream to the area to be dried.